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// force-host
// no-prefer-dynamic
#![crate_type = "proc-macro"]
#![deny(warnings)]
#![feature(proc_macro_expand, proc_macro_span)]
extern crate proc_macro;
use proc_macro::*;
use std::str::FromStr;
#[proc_macro]
pub fn expand_expr_is(input: TokenStream) -> TokenStream {
let mut iter = input.into_iter();
let mut expected_tts = Vec::new();
loop {
match iter.next() {
Some(TokenTree::Punct(ref p)) if p.as_char() == ',' => break,
Some(tt) => expected_tts.push(tt),
None => panic!("expected comma"),
}
}
let expected = expected_tts.into_iter().collect::<TokenStream>();
let expanded = iter.collect::<TokenStream>().expand_expr().expect("expand_expr failed");
assert!(
expected.to_string() == expanded.to_string(),
"assert failed\nexpected: `{}`\nexpanded: `{}`",
expected.to_string(),
expanded.to_string()
);
TokenStream::new()
}
#[proc_macro]
pub fn expand_expr_fail(input: TokenStream) -> TokenStream {
match input.expand_expr() {
Ok(ts) => panic!("expand_expr unexpectedly succeeded: `{}`", ts),
Err(_) => TokenStream::new(),
}
}
#[proc_macro]
pub fn check_expand_expr_file(ts: TokenStream) -> TokenStream {
// Check that the passed in `file!()` invocation and a parsed `file!`
// invocation expand to the same literal.
let input_t = ts.expand_expr().expect("expand_expr failed on macro input").to_string();
let parse_t = TokenStream::from_str("file!{}")
.unwrap()
.expand_expr()
.expect("expand_expr failed on internal macro")
.to_string();
assert_eq!(input_t, parse_t);
// Check that the literal matches `Span::call_site().source_file().path()`
let expect_t =
Literal::string(&Span::call_site().source_file().path().to_string_lossy()).to_string();
assert_eq!(input_t, expect_t);
TokenStream::new()
}
#[proc_macro]
pub fn recursive_expand(_: TokenStream) -> TokenStream {
// Recursively call until we hit the recursion limit and get an error.
//
// NOTE: This doesn't panic if expansion fails because that'll cause a very
// large number of errors to fill the output.
TokenStream::from_str("recursive_expand!{}")
.unwrap()
.expand_expr()
.unwrap_or(std::iter::once(TokenTree::Literal(Literal::u32_suffixed(0))).collect())
}
#[proc_macro]
pub fn echo_pm(input: TokenStream) -> TokenStream {
input
}
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